Endangered and Threatened Wildlife and Plants; 90-Day Finding for a Petition to List the Mohave Ground Squirrel as Threatened

DEPARTMENT OF THE INTERIOR

50 CFR Part 17

Endangered and Threatened Wildlife and Plants; 90-Day Finding for

a Petition to List the Mohave Ground Squirrel as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) announces the 90-

day finding on a petition to list the Mohave ground squirrel

(Spermophilus mohavensis) under the Endangered Species Act (Act) of

1973, as amended. The Service finds that the petition did not present

substantial information indicating that the petitioned action may be

warranted.

DATES: The finding announced in this document was made on August 4,

1995. Comments and materials related to this petition finding may be

submitted to the Field Supervisor at the address listed below.

ADDRESSES: Information, data, comments, or questions concerning the

status of the petitioned species should be submitted to the Field

Supervisor, Fish and Wildlife Service, Ventura Field Office, 2493

Portola Road, Suite B, Ventura, California 93003. The complete file for

this finding is available for public inspection, by appointment, during

normal business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Kate Symonds at the Ventura Field

Office (see ADDRESSES section) or at 805/644-1766.

SUPPLEMENTARY INFORMATION:

Background

Section 4(b)(3)(A) of the Endangered Species Act of 1973, as

amended (16 U.S.C. 1533 et seq.) (Act), requires that the Service make

a finding on whether a petition to list, delist, or reclassify a

species presents substantial scientific or commercial information to

indicate that the petitioned action may be warranted. This finding is

to be based on all information available to the Service at the time the

finding is made. To the maximum extent practicable, this finding is to

be made within 90 days of the date the petition was received, and the

finding is to be published promptly in the Federal Register. If the

finding is that substantial information was presented, the Service also

is required to commence a review of the status of the species.

On December 13, 1993, the Service received a petition dated

December 6, 1993, from Dr. Glenn R. Stewart of California Polytechnic

State University, Pomona, California, requesting the Service to list

the Mohave ground squirrel (Spermophilus mohavensis) as a threatened

species. The species is a category 2 candidate (November 15, 1994; 59

FR 58988), which was first included in this category on September 18,

1985. Category 2 includes taxa for which sufficient information on

biological vulnerability and threats is not currently available

indicating that listing as endangered or threatened is warranted.

The Mohave ground squirrel ranges throughout the northwest portion

of the Mojave Desert of California. The species spends about 7 months a

year, usually from August to February, estivating in burrows. Timing of

estivation is presumably related to sufficient accumulation of fat

reserves (Bartholomew and Hudson 1960, Ingles 1965, Tomich 1982).

Entrance into estivation may begin from June to September. In years

with abundant food supplies, adults may enter estivation in late June

and juveniles may enter in late July. Adults are more likely than

juveniles to enter estivation early because adults do not need to gain

as much weight as juveniles to survive the long estivation underground

(Gustafson 1993). Males tend to enter estivation earlier than females

because they do not need to put energy into milk production and feeding

of young before they store fat (Leitner and Leitner 1992). Mating

occurs soon after emergence from estivation and a litter of 4-6 young

are born after a gestation period of 28-30 days. Mohave ground

squirrels are generally less active when air temperatures drop below 88

deg.F or exceed 98.1 deg.F (Bartholomew and Hudson 1960). The diet

consists of seeds, flowers, forbs, shrubs, grasses, fungi, and

arthropods, although the species has demonstrated flexibility in

utilizing food items as annual availabilities change (Recht 1977,

Leitner and Leitner 1992).

Mohave ground squirrels have been found in all vegetation

associations and up to 5,600 feet in elevation within its 7,600 square

mile range (Hoyt 1972, Gustafson 1993). Gustafson (1993) reported that

Mohave ground squirrels have been found in Holland's (1986) communities

of Mohave wash scrub, desert sink scrub, and desert greasewood scrub.

Nonetheless, the species appears to prefer large alluvial-filled

valleys and deep, fine-to-medium textured soils vegetated with creosote

bush scrub, shadscale scrub, or alkali sink scrub wherever desert

pavement is absent (Aardahl and Roush 1985). The Mohave ground squirrel

rarely is found in mountainous or rocky terrain, or dry lake beds,

although exceptions have been recorded (Zembal and Gall 1980, Wessman

1977).

Excluding mountainous or rocky areas, and dry lake beds, the Mohave

ground squirrel habitat is distributed over an estimated 7,200 square

miles (Gustafson 1993). This figure excludes those plant communities

and soil types in which the species has never been found. Without

precise habitat information, it is difficult to assess the severity of

habitat loss. In addition, insufficient data are available on specific

habitat requirements to precisely delineate the acreage of Mohave

ground squirrel habitat. Specific information on habitat requirements

would also facilitate the rating of areas based on habitat quality.

In making a finding as to whether a petition presents substantial

commercial and scientific information to indicate the petitioned action

may be warranted, the Service must consider whether the petition is

accompanied by a detailed narrative justification [50 CFR

Sec. 424.14(b)(2)(ii)]. The regulations require the Service to

``consider whether such petition * * * [p]rovides information regarding

the status of the species over all or a significant portion of its

range'' [50 CFR Sec. 424.14(b)(2)(iii)], including current

distributional and threat information. Furthermore, the Service is

required to ``consider whether such petition * * * [i]s accompanied by

appropriate supporting documentation in the form of bibliographic

references, reprints of pertinent publications, copies of reports or

letters from authorities, and maps'' [50 CFR Sec. 424.14(b)(2)(iv)].

In assessing the substantiality of this petition, the Service

reviewed several published and unpublished studies, agency documents,

literature syntheses, commercial data, and field sighting records. The

Service also interviewed researchers and other persons familiar with

the species' biology. In addition, the petitioner was contacted to

provide additional supporting information, which he was unable to

provide. On the basis of the best scientific and commercial information

available, the Service finds that the petition did not provide reliable

data, recent or otherwise, throughout the species' range regarding

specific habitat requirements, and population abundance and trends.

Moreover, the petition did not include any data linking some activities

(e.g., rural development, off-road vehicle use, Fort Irwin training)

with long-term absence of the ground squirrel or on the extent to which

these activities may be degrading habitat. Also, the petitioner failed

to provide convincing data that grazing by domestic sheep and cattle

adversely affects the habitat of the Mohave ground squirrel. Finally,

the petition did not include any information to assess the extent and

configuration of habitat loss due to fragmentation to determine whether

this threatens the species. Therefore, given the uncertainties

associated with urban growth and other threats in the Mojave

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Desert, and the lack of credible studies on the biological status of

the species, the Service finds that the petition did not present

substantial information indicating that the listing of the Mohave

ground squirrel may be warranted. Given these data uncertainties, the

Mohave ground squirrel will remain a species of concern to the Service.

References Cited

A complete list of references used in the preparation of this

finding is available, upon request, from the Ventura Field Office (see

ADDRESSES section).

Author

The primary author of this document is Kate Symonds, Ventura Field

Office (see ADDRESSES section).

Authority

The authority for this action is the Endangered Species Act of

1973, as amended (16 U.S.C. 1531 et seq.).

Dated: August 4, 1995.

John G. Rogers,

Acting Director, Fish and Wildlife Service.

[FR Doc. 95-22171 Filed 9-6-95; 8:45 am]

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